Schwarzmüller Florian, Eisenhauer Nico, Brose Ulrich
Georg August University Göttingen, J.F. Blumenbach Institute for Zoology and Anthropology, Berliner Str. 28, Göttingen, 37073, Germany.
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany.
J Anim Ecol. 2015 May;84(3):680-691. doi: 10.1111/1365-2656.12324. Epub 2014 Dec 29.
Human activities may compromise biodiversity if external stressors such as nutrient enrichment endanger overall network stability by inducing unstable dynamics. However, some ecosystems maintain relatively high diversity levels despite experiencing continuing disturbances. This indicates that some intrinsic properties prevent unstable dynamics and resulting extinctions. Identifying these 'ecosystem buffers' is crucial for our understanding of the stability of ecosystems and an important tool for environmental and conservation biologists. In this vein, weak interactions have been suggested as stabilizing elements of complex systems, but their relevance has rarely been tested experimentally. Here, using network and allometric theory, we present a novel concept for a priori identification of species that buffer against externally induced instability of increased population oscillations via weak interactions. We tested our model in a microcosm experiment using a soil food-web motif. Our results show that large-bodied species feeding at the food web's base, so called 'trophic whales', can buffer ecosystems against unstable dynamics induced by nutrient enrichment. Similar to the functionality of chemical or mechanical buffers, they serve as 'biotic buffers' that take up stressor effects and thus protect fragile systems from instability. We discuss trophic whales as common functional building blocks across ecosystems. Considering increasing stressor effects under anthropogenic global change, conservation of these network-intrinsic biotic buffers may help maintain the stability and diversity of natural ecosystems.
如果诸如养分富集等外部压力源通过引发不稳定动态而危及整个网络的稳定性，人类活动可能会损害生物多样性。然而，一些生态系统尽管持续受到干扰，仍保持着相对较高的多样性水平。这表明一些内在特性可防止不稳定动态及由此导致的物种灭绝。识别这些“生态系统缓冲因素”对于我们理解生态系统的稳定性至关重要，也是环境和保护生物学家的一项重要工具。有观点认为，弱相互作用是复杂系统的稳定要素，但其实践相关性很少经过实验验证。在此，我们运用网络和异速生长理论，提出了一个全新概念，用于先验识别那些通过弱相互作用缓冲外部诱导的种群振荡增加所导致的不稳定性的物种。我们在一个使用土壤食物网模式的微观实验中对模型进行了测试。结果表明，在食物网基部取食的大体型物种，即所谓的“营养级鲸鱼”，可以缓冲生态系统免受养分富集引发的不稳定动态影响。类似于化学或机械缓冲器的功能，它们充当“生物缓冲器”，吸收压力源的影响，从而保护脆弱系统免于不稳定。我们将营养级鲸鱼视为跨生态系统的常见功能构件进行讨论。考虑到人为全球变化下压力源影响不断增加，保护这些网络内在的生物缓冲器可能有助于维持自然生态系统的稳定性和多样性。
